BitTorrent: Do most corporate networks block it?

There have been estimates that over 35% of all Internet traffic is consumed by BitTorrent. Naturally, we have to be careful with those numbers because the files being transferred on most of the torrents are audio, music, and video files, which are exponentially larger than most e-mails or HTML pages. Still, this 35% stat shows the sheer scale of traffic that BitTorrent can handle, and it also shows the large appetite that Internet users have for multimedia  especially free multimedia.

So my question is whether most corporate networks are blocking BitTorrent. I know several companies that do, but I'm wondering how widespread the phenomenon is, and also whether BitTorrent software and users have figured out ways to get around the restrictions put in place by IT departments.

Of course, that leads me to another question: How will IT departments distinguish between good BitTorrent traffic and bad BitTorrent traffic? While it might be easy to just ban it altogether, that might not be a long term solution if legitimate files start getting transferred as torrents.

I have a lot more questions than answers the more I think about this. I'm hoping that TechRepublic readers can chime in and provide some thoughts and responses. If nothing else, please respond whether you are currently blocking (or trying to block) BitTorrent traffic on your network.